[robocop10mm]

On the 7600 the front swivel should attach to the screw at the end of the forearm, not the barrel.

 

[robocop10mm]

I looked at Uncle Mikes site and saw the newer 7600 swivels use a barrel band arrangement. What caliber is your gun? I cannot imagine every barrel has the same OD (especially the 35 Whelen). I would contact Uncle Mikes for further guidance.